Oh and while I'm at it, let's take a quick look at the footprints of two base OS's shall we:
Windows XP: over 1GB
Amiga OS 3.1: under 10MB
The sheer size alone should be indicative of load times. Sure the Pentium had ooodles more raw processing power, but it also has a truckload more to load. A while back I installed Win98 on my Athlon XP 4000+, it loaded so fast I didn't even get a 98 splash screen, the machine had POSTed and loaded 98 in just over 10 seconds.
Additionally, in your case, you're running a Dell. More than likely, you're using the default install of XP that came with it, hardly a fully optimized environment to begin with. Dell, HP, etc. etc. bloat there machines to the hilt with crap, no matter what you do, you will never clean them up properly. The only option is to format and do a clean install of Windows from a retail CD. People who know me will testify that I'm not the biggest fan of Windows, however, I really grow tired of people bashing it with little or no insight into what they are actually saying.
Edit...One more thing, if you really hate Windows that much, put your money where your mouth is and do what I did, buy a mac, actually, buy several, as in my case.